Mixers are known to attain dry mixtures of powdery materials as well as homogeneous slurries of such mixtures with a suitable liquid.
Also known is that, in its basic construction, a traditional mixer consits of a substantially cylindrical container or drum inside which a shaft is disposed for engagement with a motor-reducer and provided with one or more transversal arms to each of which a paddle is connected fixedly or otherwise rotatively for rotation about an axis parallel to the same drive shaft. The term "paddle" herein referring both to an element intended to operate the proper mixing, and an element intended to scrape the bottom or the inner wall of the drum. The drum is provided with a loading hopper allowing the introduction from above of the materials to be mixed, and with an outlet mouth having a manually operated opening/closing gate. The output of the mixture from the drum usually occurs with the mixer paddles being in motion to ease the discharge thereof.
However, experience has shown that the known mixers exhibit some drawbacks, among which: a poor self-cleaning of the inner walls and of the bottom of the drum; a reduced ability of the mixture-discharging gate to provide sealing especially with respect to liquids; an insufficient distribution of the liquid over the materials to be mixed; the absence of safety measures for the introduction of materials into the drum when the latter is made accessible.